Multi-stage centrifugal pump

Abstract

A multistage centrifugal pump relates to the technical field of centrifugal pumps and comprises a pump body assembly A and a pump body assembly B. The pump body assembly A comprises an impeller A, a center gathering guide vane A and a centrifugal guide vane A. The centrifugal guide vane A is located at an outlet of the impeller A, and the center gathering guide vane A is located at an inlet of the impeller A; the pump body assembly B comprises an impeller B, a center gathering guide vane B and a centrifugal guide vane B, the centrifugal guide vane B is located at an outlet of the impeller B, and the center gathering guide vane B is located at an inlet of the impeller B; the position of the centrifugal guide vane A corresponds to the position of the center gathering guide vane B. The position of the middle centrifugal guide vane B corresponds to the position of the center gathering guide vane A. Fluid alternately receives centrifugal acting force on the impeller A and the impeller B, and the direction of the fluid is changed through the alternate action of the centrifugal guide vane A, the center gathering guide vane B, the centrifugal guide vane B and the center gathering guide vane A. In the whole flowing process, the potential energy of the fluid is kept to the maximum degree, and therefore the pump efficiency is higher. And meanwhile, the axial forces of the two pump shafts can be balanced through the lever.

Description

Technical Field

[0001] The invention belongs to the technical field of centrifugal pumps, and in particular relates to a multi-stage centrifugal pump. Background Art

[0002] A multistage centrifugal pump is a combination of two or more centrifugal pumps with the same function. In terms of the fluid channel structure, the medium pressure relief port of the first stage is connected to the inlet of the second stage, and the medium pressure relief port of the second stage is connected to the inlet of the third stage. Such a series connection mechanism forms a multistage centrifugal pump. The centrifugal pump includes a multistage impeller and a multistage guide vane matched therewith. Water is subjected to centrifugal force on the impeller, generating flow potential in the direction of the centrifugal force. The defects of the existing multistage centrifugal pump are: the water presents a "snake-shaped" flow path in the process of reaching the rear end of the guide vane from the front end of the guide vane, and the direction of the flow potential energy of the water has to change. The change in the direction of the water flow potential undoubtedly reduces the pump efficiency. In addition, the existing multistage needs to be provided with a balancing disc to offset the axial force generated by the rotation of the impeller. There is a certain gap between the balancing disc and the balancing ring seat. When the centrifugal pump is working, the balancing disc is pushed open under the action of the liquid pressure. However, at the beginning of the pump startup, the balancing disc and the balancing ring are in a friction state, and the friction will damage the balancing disc. In addition, once the balancing disc is stuck, it will be difficult to push it open, which seriously affects the force balance of the pump shaft. Therefore, the existing balancing ring is unstable. Summary of the invention

[0003] In order to solve the problem that the water flow potential energy in a multi-stage centrifugal pump changes 180 degrees when passing through the guide vane, affecting the pump efficiency, and also to solve the problem that the balancing disc is unstable, the present invention provides a multi-stage centrifugal pump. On the one hand, the present invention changes the arrangement of the impellers from a single-row impeller to a double-row impeller, and the water flows crosswise between the two rows of impellers and are centrifugally acted upon, and the direction of the flow potential energy of the water flow does not change significantly, thereby improving the pump efficiency. On the other hand, the two rows of impellers have two pump shafts, and the ends of the two pump shafts are balanced by levers to ensure stable balancing.

[0004] The technical solution provided by the present invention is: a multi-stage centrifugal pump, including a pump body assembly A and a pump body assembly B, the two pump body assemblies are arranged in parallel, the pump body assembly A includes a water inlet section, a middle section A, a pump shaft A, an impeller A, a concentric guide vane A and a centrifugal guide vane A, the impeller A is fixedly installed on the pump shaft A, the impeller A rotates with the pump shaft A, the centrifugal guide vane A is located at the outlet of the impeller A, the liquid thrown out by the impeller A is collected, and then spirally introduced into the pump body assembly B, the centrifugal guide vane A is fixedly installed The centrifugal guide vane A is installed in the middle section A, and the centrifugal guide vane A is located at the inlet of the impeller A. The centrifugal guide vane A collects the fluid from the pump body assembly B and sends it to the impeller A. The centrifugal guide vane A is fixedly installed in the middle section A, and the water inlet section is arranged upstream of the first-stage impeller A; the pump body assembly B includes a middle section B, a pump shaft B, an impeller B, a centrifugal guide vane B, a centrifugal guide vane B and a water outlet section. The impeller B is fixedly installed on the pump shaft B, and the impeller B rotates with the pump shaft B. The centrifugal guide vane B is located at the outlet of the impeller B. The centrifugal guide vane The blade B is fixedly installed in the middle section B, the focusing guide vane B is located at the inlet of the impeller B, the focusing guide vane B is fixedly installed in the middle section B, and the water outlet section is arranged downstream of the last-stage centrifugal guide vane B; the position of the centrifugal guide vane A in the pump body assembly A corresponds to the position of the focusing guide vane B in the pump body assembly B, and the corresponding middle section A and middle section B are provided with a connecting port for connecting the centrifugal guide vane A with the focusing guide vane B, and the position of the centrifugal guide vane B in the pump body assembly B corresponds to the position of the focusing guide vane A in the pump body assembly A, and the corresponding middle section A and middle section B are provided with a connecting port for connecting the centrifugal guide vane B with the focusing guide vane A; the fluid generates flow potential energy through the centrifugal action of the impeller A, and then flows out from the centrifugal guide vane A and enters the focusing guide vane B, and then flows out from the centrifugal guide vane B through the centrifugal action of the impeller B and enters the focusing guide vane A, and the above path is repeated, the direction of the fluid flow potential energy changes little, so that the flow potential energy of the fluid is maintained to the greatest extent, thereby reducing the loss of pump power and improving pump efficiency.

[0005] Since the present application has two pump shafts, a lever is provided in the pump body assembly at the ends of the pump shaft A and the pump shaft B. The pump shaft A and the pump shaft B respectively cooperate with the two ends of the lever through thrust bearings, thereby ensuring that the axial forces acting on the pump shaft A and the pump shaft B are balanced, thereby eliminating the balancing plate and avoiding the problems of balancing plate wear and poor reliability.

[0006] A further technical solution is: the middle section A with the centrifugal guide vane A is a cylinder, and the middle section B with the converging guide vane B is a crescent cylinder, and the two are fitted together; the middle section B with the centrifugal guide vane B is a cylinder, and the middle section A with the converging guide vane A is a crescent cylinder, and the two are fitted together; thereby reducing the overall volume and shortening the wheelbase between the pump shaft A and the pump shaft B.

[0007] A further technical solution is: a front common connecting section is provided at the front end of the water inlet section, and the first-stage middle section B and the water inlet section are commonly connected to the front common connecting section; a rear common connecting section is provided at the rear end of the water outlet section, and the last-stage middle section A and the water outlet section are commonly connected to the rear common connecting section, and the middle part of the lever is hinged to the rear common connecting section.

[0008] A further technical solution is: the pump shaft A passes through the lever, a tightening ring is arranged on the pump shaft A, a thrust bearing is arranged between one side of the tightening ring and the lever, a groove is arranged on the other side of the tightening ring, an oblique plug is arranged in the groove, the pump shaft A is provided with an oblique groove, the oblique plug is inserted into the oblique groove along the radial direction of the pump shaft A, so that the axial position of the tightening ring on the pump shaft A is changed by the insertion of the oblique plug, the tightening ring on the outer edge of the groove is provided with a countersunk screw, the inner side of the countersunk screw is against the oblique plug, so as to push the oblique plug to the oblique direction. The pump shaft B passes through the lever, a tightening ring is arranged on the pump shaft B, a thrust bearing is arranged between one side of the tightening ring and the lever, a groove is arranged on the other side of the tightening ring, an oblique plug is arranged in the groove, the pump shaft B has an oblique groove, the oblique plug is inserted into the oblique groove along the radial direction of the pump shaft B, so that the axial position of the tightening ring on the pump shaft B is changed by the insertion of the oblique plug, the tightening ring on the outer edge of the groove has a countersunk screw, the inner side of the countersunk screw rests on the oblique plug, so as to push the oblique plug into the oblique groove. The setting of the oblique plug can not only make the tightening ring rotate synchronously with the pump shaft, but also adjust the axial position of the tightening ring on the pump shaft through the inclined surface, so as to ensure that the tightening ring and the lever can be close.

[0009] Compared with the prior art, the beneficial effects of the present invention are: 1. In the prior art, when the fluid flows from the front end to the rear end of a guide vane, the direction of the fluid changes 180 degrees. Since the direction change is very large, the flow potential energy of the fluid is severely weakened. In order to obtain the flow potential energy, the next-stage impeller must be used to assist it again. Therefore, the pump efficiency of the existing multi-stage centrifugal pump is suppressed. The present application sets two sets of pump body assemblies in parallel, and the fluid alternately flows between the two sets of pump body assemblies. During the alternating flow, the direction of the fluid changes little, and the flow potential energy is maintained to the greatest extent. Excessive assistance from the lower-stage impeller is not required, so the pump efficiency of the present invention is higher and more energy-saving.

[0010] 2. Since the present application has two parallel pump shafts, the axial forces on the two pump shafts can be balanced by a lever, so the present application no longer needs to set up a balancing plate, thus avoiding the problem of low stability of the balancing plate when in use.

[0011] 3. The setting of the oblique plug in the present application can not only make the top tightening ring and the pump shaft rotate synchronously, but also adjust the axial position of the top tightening ring on the pump shaft through the inclined surface to ensure that the top tightening ring and the lever are close together. The structural design is ingenious and reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0013] Figure 2 It is a schematic diagram of the positional relationship among the pump shaft, impeller, centrifugal guide wheel and concentrating guide wheel in the present invention.

[0014] Figure 3 It is a schematic diagram of the structure of each section of the outer shell of the pump body assembly in the present invention.

[0015] Figure 4 yes Figure 3 Cross-sectional view of AA.

[0016] Figure 5 It is a partial enlarged view of the lever in the present invention.

[0017] In the figure: 1. front cover; 2. front common section; 3. rear common section; 4. tail cover; 5. concentric guide vane B; 6. impeller B; 7. centrifugal guide vane B; 8. pump shaft B; 9. pump shaft A; 10. concentric guide vane A; 11. impeller A; 12. centrifugal guide vane A; 13. middle section B; 14. water outlet section; 15. middle section A; 16. water inlet section; 17. connecting port; 18. lever; 19. thrust bearing; 20. tightening ring; 21. countersunk screw; 22. oblique plug. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] This embodiment includes two pump body assemblies, which are respectively referred to as pump body assembly A and pump body assembly B, and the two pump body assemblies are arranged in parallel.

[0020] The pump body assembly A includes a water inlet section 16, a middle section A15, a pump shaft A9, an impeller A11, a concentrating guide vane A10 and a centrifugal guide vane A12. The impeller A11 is fixedly mounted on the pump shaft A9, and the impeller A11 rotates with the pump shaft A9. The centrifugal guide vane A12 is located at the outlet of the impeller A11, collects the liquid thrown out by the impeller A11, and then spirally introduces it into the concentrating guide vane B5 in the pump body assembly B. The centrifugal guide vane A12 is fixedly mounted in the middle section A, and the concentrating guide vane A10 is located at the inlet of the impeller A11. The concentrating guide vane A10 collects the fluid from the pump body assembly B and sends it to the impeller A11. The concentrating guide vane A10 is fixedly mounted in the middle section A. The water inlet section 16 is arranged upstream of the first-stage impeller A11.

[0021] The pump body assembly B includes a middle section B13, a pump shaft B8, an impeller B6, a concentrating guide vane B5, a centrifugal guide vane B7 and a water outlet section 14. The impeller B6 is fixedly mounted on the pump shaft B8, and the impeller B6 rotates with the pump shaft B8. The centrifugal guide vane B7 is located at the outlet of the impeller B6, and collects the liquid thrown out by the impeller B6, and then spirally introduces it into the concentrating guide vane A10 in the pump body assembly A. The centrifugal guide vane B7 is fixedly mounted in the middle section B. The concentrating guide vane B5 is located at the inlet of the impeller B6. The concentrating guide vane B5 collects the fluid from the pump body assembly A and sends it to the impeller B6. The concentrating guide vane B5 is fixedly mounted in the middle section B, and the water outlet section 14 is arranged downstream of the last-stage centrifugal guide vane B7. Figure 2 The arrows in the figure indicate the flow path of the fluid in this embodiment.

[0022] The position of the centrifugal guide vane A12 in the pump body assembly A corresponds to the position of the concentrating guide vane B5 in the pump body assembly B. The corresponding intermediate sections A and B are provided with a connecting port 17 for connecting the centrifugal guide vane A12 with the concentrating guide vane B5. Figure 3 and Figure 4 As shown, the position of the centrifugal guide vane B7 in the pump body assembly B corresponds to the position of the concentrating guide vane A10 in the pump body assembly A, and the corresponding middle section A and middle section B are provided with a connecting port 17 for connecting the centrifugal guide vane B7 with the concentrating guide vane A10. The fluid generates flow potential energy through the centrifugal action of the impeller A11, then flows out from the centrifugal guide vane A12 and enters the concentrating guide vane B5, then flows out from the centrifugal guide vane B7 and enters the concentrating guide vane A10 through the centrifugal action of the impeller B6, and repeats the above path. The direction of the fluid flow potential energy changes little, so that the flow potential energy of the fluid is maintained to the maximum extent, thereby reducing the loss of pump power and improving pump efficiency.

[0023] Since the present application has two pump shafts, a lever 18 is provided in the pump body assembly at the ends of the pump shaft A9 and the pump shaft B8. The pump shaft A9 and the pump shaft B8 respectively cooperate with the two ends of the lever 18 through thrust bearings 19, thereby ensuring that the axial forces on the pump shaft A9 and the pump shaft B8 are balanced, thereby eliminating the need for a balancing plate, avoiding the problems of balancing plate wear and poor reliability in use. In the present application, the number of impellers A11 and the number of impellers B6 may be different. In this case, it is only necessary to define the lever arm length of the lever 18 according to the difference in the number of impellers at the beginning of the design.

[0024] The middle section A with the centrifugal guide vane A12 installed is a cylinder, and the middle section B with the focusing guide vane B5 installed is a crescent cylinder, and the two are fitted together; the middle section B with the centrifugal guide vane B7 installed is a cylinder, and the middle section A with the focusing guide vane A10 installed is a crescent cylinder, and the two are fitted together; the purpose of designing the crescent cylinder is to reduce the overall volume of the multi-stage centrifugal pump, and also to shorten the wheelbase between the pump shaft A9 and the pump shaft B8. When the wheelbase is reduced, the force arm of the lever 18 is reduced, and the probability of its bending is greatly reduced.

[0025] A front common section 2 is provided at the front end of the water inlet section 16, and the first-stage middle section B and the water inlet section 16 are commonly connected to the front common section 2; a rear common section 3 is provided at the rear end of the water outlet section 14, and the final-stage middle section A and the water outlet section 14 are commonly connected to the rear common section 3, and the middle part of the lever 18 is hinged on the rear common section 3. Since the middle section has a cylindrical shape and a crescent shape, the front common section 2 and the rear common section 3 are provided to enable the front cover 1 and the tail cover 4 to be more easily flanged and installed.

[0026] The pump shaft A9 passes through the lever 18, and a tightening ring 20 is arranged on the pump shaft A9. A thrust bearing 19 is arranged between one side of the tightening ring 20 and the lever 18, and a groove is arranged on the other side of the tightening ring 20. An oblique plug 22 is arranged in the groove. The pump shaft A9 is provided with an oblique groove, and the oblique plug 22 is inserted into the oblique groove along the radial direction of the pump shaft A9, so that the axial position of the tightening ring 20 on the pump shaft A9 is changed by the insertion of the oblique plug 22. The tightening ring 20 at the outer edge of the groove is provided with a countersunk screw 21, and the inner side of the countersunk screw 21 abuts against the oblique plug 22, so as to push the oblique plug 22 to be inserted into the oblique groove; The pump shaft B8 passes through the lever 18, and a tightening ring 20 is arranged on the pump shaft B8. A thrust bearing 19 is arranged between one side of the tightening ring 20 and the lever 18, and a groove is arranged on the other side of the tightening ring 20. An oblique plug 22 is arranged in the groove. The pump shaft B8 has an oblique groove, and the oblique plug 22 is inserted into the oblique groove along the radial direction of the pump shaft B8, so that the axial position of the tightening ring 20 on the pump shaft B8 is changed by the insertion of the oblique plug 22. The tightening ring 20 at the outer edge of the groove has a countersunk screw 21, and the inner side of the countersunk screw 21 abuts against the oblique plug 22, so as to push the oblique plug 22 into the oblique groove. The setting of the oblique plug 22 can not only make the tightening ring 20 rotate synchronously with the pump shaft, but also adjust the axial position of the tightening ring 20 on the pump shaft through the inclined surface, so as to ensure that the tightening ring 20 and the lever 18 can be close together during installation.

Claims

1. A multistage centrifugal pump, characterized in that: The invention comprises a pump body assembly A and a pump body assembly B. The two pump body assemblies are arranged in parallel. The pump body assembly A comprises a water inlet section (16), a middle section A (15), a pump shaft A (9), an impeller A (11), a converging guide vane A (10) and a centrifugal guide vane A (12). The impeller A (11) is fixedly mounted on the pump shaft A (9). The centrifugal guide vane A (12) is located at the outlet of the impeller A (11). The centrifugal guide vane A (12) is fixedly mounted in the middle section A. The converging guide vane A (10) is located at the impeller A (11). The pump body assembly B comprises a middle section B (13), a pump shaft B (8), an impeller B (6), a concentrating guide vane B (5), a centrifugal guide vane B (7) and a water outlet section (14). The impeller B (6) is fixedly mounted on the pump shaft B (8). The centrifugal guide vane B (7) is located at the outlet of the impeller B (6). The centrifugal guide vane B (7) is fixedly mounted in the middle section B. The concentrating guide vane A (10) is fixedly mounted in the middle section A. The water inlet section (16) is arranged upstream of the first-stage impeller A (11). The pump body assembly B comprises a middle section B (13), a pump shaft B (8), an impeller B (6), a concentrating guide vane B (5), a centrifugal guide vane B (7) and a water outlet section (14). The impeller B (6) is fixedly mounted on the pump shaft B (8). The centrifugal guide vane B (7) is located at the outlet of the impeller B (6). The centrifugal guide vane B (7) is fixedly mounted in the middle section B. The guide vane B (5) is located at the inlet of the impeller B (6), the concentrating guide vane B (5) is fixedly installed in the middle section B, and the water outlet section (14) is arranged downstream of the final centrifugal guide vane B (7); the position of the centrifugal guide vane A (12) in the pump body assembly A corresponds to the position of the concentrating guide vane B (5) in the pump body assembly B, and the corresponding middle section A and middle section B are provided with a connecting port (17) for connecting the centrifugal guide vane A (12) and the concentrating guide vane B (5), and the position of the centrifugal guide vane B (7) in the pump body assembly B corresponds to the position of the centrifugal guide vane B (12) in the pump body assembly B. Corresponding to the position of the centrifugal guide vane A (10) in the pump body assembly A, the corresponding intermediate section A and intermediate section B are provided with a communication port (17) for connecting the centrifugal guide vane B (7) with the centrifugal guide vane A (10); a lever (18) is provided in the pump body assembly at the ends of the pump shaft A (9) and the pump shaft B (8); the pump shaft A (9) and the pump shaft B (8) are respectively engaged with the two ends of the lever (18) through thrust bearings (19), thereby ensuring that the axial forces acting on the pump shaft A (9) and the pump shaft B (8) are balanced.

2. A multistage centrifugal pump according to claim 1, characterized in that: The middle section A on which the centrifugal guide vane A (12) is installed is a cylinder, and the middle section B on which the concentrating guide vane B (5) is installed is a crescent cylinder, and the two are arranged in a close fit; the middle section B on which the centrifugal guide vane B (7) is installed is a cylinder, and the middle section A on which the concentrating guide vane A (10) is installed is a crescent cylinder, and the two are arranged in a close fit; thereby, the overall volume is reduced and the wheelbase between the pump shaft A (9) and the pump shaft B (8) is shortened.

3. A multistage centrifugal pump according to claim 1, characterized in that: A front common connecting section (2) is provided at the front end of the water inlet section (16), and the first-stage middle section B and the water inlet section (16) are connected to the front common connecting section (2); a rear common connecting section (3) is provided at the rear end of the water outlet section (14), and the last-stage middle section A and the water outlet section (14) are connected to the rear common connecting section (3), and the middle part of the lever (18) is hinged to the rear common connecting section (3).

4. A multistage centrifugal pump according to claim 3, characterized in that: The pump shaft A (9) passes through the lever (18), a tightening ring (20) is arranged on the pump shaft A (9), a thrust bearing (19) is arranged between one side of the tightening ring (20) and the lever (18), a groove is arranged on the other side of the tightening ring (20), an oblique plug (22) is arranged in the groove, the pump shaft A (9) is provided with an oblique groove, the oblique plug (22) is inserted into the oblique groove along the radial direction of the pump shaft A (9), so that the axial position of the tightening ring (20) on the pump shaft A (9) is changed by the insertion of the oblique plug (22), the tightening ring (20) at the outer edge of the groove is provided with a countersunk screw (21), the inner side of the countersunk screw (21) abuts against the oblique plug (22), so that the oblique plug (22) is pushed to be inserted into the oblique groove; The pump shaft B (8) passes through the lever (18), a tightening ring (20) is arranged on the pump shaft B (8), a thrust bearing (19) is arranged between one side of the tightening ring (20) and the lever (18), a groove is arranged on the other side of the tightening ring (20), an oblique plug (22) is arranged in the groove, the pump shaft B (8) has an oblique groove, the oblique plug (22) is inserted into the oblique groove along the radial direction of the pump shaft B (8), so that the axial position of the tightening ring (20) on the pump shaft B (8) is changed by the insertion of the oblique plug (22), the tightening ring (20) at the outer edge of the groove has a countersunk screw (21), the inner side of the countersunk screw (21) abuts against the oblique plug (22), so that the oblique plug (22) is pushed to be inserted into the oblique groove.

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